Electrical devices (for example electrical tools) often have switches in order to manually switch the devices on and off. Here, it is known to detect a position of said switches, for which purpose particular electrical and electronic components are used.
By way of example, it is important to detect the switch position because, in the event that a mains plug of the device is plugged into a socket when the switch is switched on, the electrical device may not start up or turn on. This operating procedure is known as “restart protection” and is partially defined in standards. Even in the event of temporary voltage drops during operation, the device may not subsequently be turned on again in an undefined manner. If the switch is open, a controlling semiconductor in principle may not be triggered.
Depending on the hazardousness of the device, it may also be required that redundant switch detection is to be provided by means of which an increased level of safety of the device is supported.
DE 10 2011 088 411 A discloses a circuit arrangement and a method for detecting a switch position. In that case, a microcontroller is programmed to compare a voltage present at a connection to a reference voltage and, on the basis of said comparison, to determine whether the switch is open or closed. What is disadvantageous in that case is that a specific type of microcontroller with an internal voltage reference or a microcontroller with an external voltage reference is necessary.